1. Field of the Invention
The present invention relates to an information retrieval system for retrieving desired information from a record medium such as a film having information recorded thereon.
2. Description of the Prior Art
In a film used in a retrieval apparatus incorporated in a microfilm reader, a counting mark is printed on an edge of each frame of the film and desired information on the film is automatically retrieved by counting the marks.
In such a retrieval apparatus, the marks on the film are illuminated by a lamp, the light flux from the marks when the film is moved is detected by a mark detector having a photo-electric conversion element, output signals of the mark detector are counted by a counter, the count of the counter is compared with a desired frame number inputted by a keyboard by a comparator, and the comparator generates a stop signal to a drive control circuit when both counts are equal to stop a drive system for the film so that the desired frame is stopped at a predetermined position to project it on a screen.
Many types of films are used in such an information retrieval system.
FIGS. 1A and 1B show examples of the films used in the retrieval apparatus. A film F1 shown in FIG. 1A has first, small marks MP printed on the edge of lower class information frames and second large marks MF printed on the edge of higher class information frames. The second marks MF are used to retrieve information classified in a medium class (high class) and the first marks MP are used to retrieve information classified in a minor class (low class). For example, when part drawings of an automobile are recorded on a film, the structure of the automobile is divided into several units and the frames having developed views of the respective units recorded thereon are marked with the second marks MF indicating the medium class, and part charts, part numbers and part prices of each unit are recorded on one or more frames following that which has the developed view of the unit recorded thereon, and the first marks MP indicating the minor class are marked on the edges of the frames for the part charts, etc. When such a film is used, a frame having a desired unit developed view recorded thereon can be retrieved by detecting the second mark MF, and frames having desired part charts, part numbers or part prices recorded thereon in the desired unit can be retrieved by detecting the first marks MP. Assuming that one unit constitutes one group of information, one group of information consists of one or more frames on which images of associated information contents are recorded.
A film F2 shown in Fig. 1B has first small marks MP for a low class, second medium marks MF for an intermediate class and third large marks MB for a high class. The third mark MB is used to retrieve information of a major class, the second mark MF is used to retrieve information of a medium class and the first mark MP is used to retrieve information of a minor class. For example, when part charts of automobiles are recorded on a film, three types of marks are selectively recorded on the edges of the respective frames so that types of automobiles, unit developed charts and part charts can be retrieved. When this film is used, a desired automobile construction chart can be retrieved by detecting the third mark MB, a desired unit developed chart can be retrieved by detecting the second mark MF and a desired part chart can be retrieved by detecting the first mark MP. Hereinafter, the first mark MP indicating the low class information is referred to as a page mark, the second mark MF indicating the medium class information is referred to as a file mark and the third mark MB indicating the high class information is referred to as a batch mark. When information is retrieved by using the film having two or more types of marks, the information in the desired class can be automatically retrieved by counting the marks of the selected class. For example, a frame of a desired file can be retrieved by counting the file marks, and a frame of a desired batch can be retrieved by counting the batch marks.
Besides the automatic retrieval method for retrieving the desired information described above, there is another method in which if an address of a low class frame in desired information is not known, it is retrieved by intermittently feeding the frames having the low class marks attached thereto and displaying the information of the frames on a screen frame by frame. (This retrieval method is called a Browsing retrieval.) When required information is to be retrieved by the Browsing retrieval by watching each frame in the desired file (or batch), the film is stopped for a predetermined time period each time the page mark (or file mark) is detected, then the film is fed and stopped again for the predetermined time period when the next page mark (or file mark) is detected, and the above operation is repeated for each frame. However, if the requested information is overlooked, the user notices that fact only while viewing information in another file (or batch) or when the film has been completely fed from a supply reel to a take-up reel.
In the automatic retrieval method in which an address (data) of a desired information frame is entered by information frame address input means such as a keyboard, if an incorrect address, for example, an address which does not exist in the film under retrieval, is entered by mistake, the misentry is only detected after the entire film has been fed from the supply reel to the take-up reel. Thus, a long time is required before the correct address is reentered and the correct information is retrieved. Therefore, work efficiency is low.